JPH03281958A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To form an optimum concentration of air fuel mixture in response to operating conditions by detecting the quantity of intake air with high accuracy based on crank case inner pressure, intake air temperature and the like in accordance with a specified formula in the fuel injection device of a crank case pressurizing 2 cycle internal combustion engine. CONSTITUTION:When an internal combustion engine 10 is in operation, detected signals from a pressure detecting device 52, a crank angle detecting device 54 and an intake air temperature detecting device 56 are inputted into an air quantity operating device 58, the quantity of intake air G is obtained based on a formula I by the use of crank case inner pressure P1 at the time when a scavenge port is almost opened, crank case inner pressure P2 when the scavenge port is almost opened, and intake air temperature T0. An optimum fuel supply for operating conditions is then computed by an injection control device 60 based on the operation result G of the air quantity operation device 58, the rotating angle theta of a crank shaft 20 and various control signals indicating the operating conditions so that the signal for the optimum fuel supply is thereby outputted to an injection valve 46.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection device for a two-stroke internal combustion engine with crank chamber preload.

[Prior Art] In a fuel injection device used in an internal combustion engine, it is necessary to control the amount of fuel injection according to the amount of intake air to obtain the optimum air-fuel mixture concentration corresponding to the operating state.

However, as a conventional fuel injection device,
The method described in Publication No. 75 has been proposed. This fuel injection device, in a two-stroke internal combustion engine with a preloaded crank chamber, uses intake air to This intake air amount is used to determine the fuel injection amount.

In other words, the amount of intake air is equal to the weight of air in the crank chamber at the start of the scavenging stroke minus the weight of air remaining in the crank chamber at the end of the scavenging stroke, and according to Japanese Patent Application Laid-Open No. 59-5875, , the above-mentioned P1 is adopted as the representative value of the air weight in the crank chamber at the beginning of the injection stroke, and the above-mentioned P2 is adopted as the representative value of the air weight remaining in the crank chamber at the end of the scavenging stroke, and the intake air amount is determined by PI-P2. This is what we sought.

[Problems to be Solved by the Invention] Silently, in an actual internal combustion engine, the intake air changes polytropically, so the conventional technology that simply calculates the intake air amount from Pi-P2 has low accuracy in detecting the intake air amount. This means that the control accuracy of controlling the fuel injection amount in accordance with the actual intake air amount is low, making it difficult to form a mixture concentration that corresponds to the operating state.

The present invention detects the amount of intake air with high accuracy in a fuel injection device for a two-stroke internal combustion engine with crank chamber preloading, and as a result improves the control accuracy of controlling the amount of fuel injection according to the actual amount of intake air. The purpose is to form the optimum mixture concentration corresponding to the operating conditions.

[Means for Solving the Problems] The present invention provides a crank chamber pre-pressure type two-stroke internal combustion engine in which intake air is pre-pressurized in a crank chamber and the pre-pressurized intake air is supplied to a combustion chamber from a scavenging port. A pressure detection device that detects the intake air temperature, an intake air temperature detection device that detects the intake air temperature, and detecting signals from the pressure detection device and the intake air temperature detection device are obtained to determine the crank room pressure Pl when the scavenging port is near the opening, and the crankshaft when the scavenging port is near the closing. Indoor pressure P2. Using the intake air temperature TO, an air amount calculation device calculates the intake air amount G based on the following formula or a simplified formula/table of the following formula, and calculates the fuel injection amount based on the calculation result of the air amount calculation device. The injection control device is configured to include an injection control device that makes a decision.

G=h [f(P1, P2), T0] However, f (
P1, P2) = P2 [(Pl/P2)'/”-1
] n: Volitrobe index [effect] The weight of intake air is equal to the weight of the air flowing out from the crank chamber into the combustion chamber during the scavenging stroke.In other words, the weight of the air in the crank chamber at the start of the scavenging stroke (near the opening of the scavenging port) This is the weight of the air remaining in the crank chamber at the end of the scavenging stroke 11e (near the closing of the scavenging port) or the weight of the intake air. This can be expressed as the following equation (1).

GAir=G1-G2,,
, (1) GAir: Intake air weight G1: Air weight at the start of the scavenging stroke G2: Air weight at the end of the scavenging stroke In the aforementioned Japanese Patent Application Laid-open No. 59-5875, the value indicating G1 is the value in the crank chamber near the scavenging port opening. The crank chamber pressure P2 near the scavenging port m was used as the value indicating the pressures P1 and G2. For this reason, P 1 - P 2 was used as a parameter for determining the intake air weight.

However, in an actual internal combustion engine, the intake air changes polytropically, so the value indicating the air weight G is influenced by the crank chamber pressure P and the crank chamber hot water temperature T.
/T. That is, the parameters for determining the intake air weight are as shown in equation (2) below.

TI T2 Tl: Temperature inside the crankshaft near the opening of the scavenging port T2: Temperature inside the crankshaft near the closing of the scavenging port Tl = 72, then PI-P2 shown in JP-A No. 59-5875 may be used as a parameter. However, in an actual internal combustion engine, TI=T2 does not hold, so the accuracy of intake air superimposition determined using PI-P2 as a parameter decreases.

Therefore, accuracy can be improved by determining the intake air weight using the above equation (2) as a parameter.

However, it is difficult to accurately and responsively measure the temperature inside the crankshaft, which constantly changes with the crank angle.

Therefore, the above equation (2) is modified as follows.

Here, since the air taken into the internal combustion engine undergoes a polytropic change, the relationship between T1 and T2 is as shown in equation (3) below.

n: Polytropic index Also, since T2 is almost equal to the intake air temperature TO, the above (2
) is as shown in equation (4) below.

(4) As a result, the intake air weight G can be determined by a function using the intake air temperature TO and the function f (P1, P2) of Pl and P2 as parameters, as shown in equation (5) below.

(3=)1 [f(P1, P2), T0]
(5) h: Experimental formula determined from experiments In the implementation of the present invention, since the above G is used to control the operation of the internal combustion engine, it is necessary to increase the processing speed. For this reason, the functions f and h described above may be converted into simplified expressions that do not include complex exponents, such as polynomials, or may be used by converting them into various types of f corresponding to the various types of TOlP1 and P2 that vary widely.
It is also possible to use a map in which (P1, P2) and G are prepared in advance in the form of a numerical table, graph, or the like.

[Example] FIG. 1 is a control system diagram showing one embodiment of the present invention.

In FIG. 1, reference numeral 10 is a two-stroke internal combustion engine with preloaded crank chamber, 12 is a cylinder, 12A is a combustion chamber, 14 is a piston, 16 is a spark plug, 18 is a crankcase, 20 is a crankshaft, or 22 is a connecting rod. . crank case 18
A crank chamber 24 is formed therein.

26 is an intake pipe, and this intake pipe 26 is connected to the intake boat 30 via a reed valve 28.

32 is an exhaust boat, and 34 is an exhaust pipe. Incidentally, a scavenging boat 36 is opened in the cylinder 12, and this scavenging boat 36
communicates with the crank chamber 24 through a scavenging passage 38.

40 is a fuel tank, 42 is a strainer for removing dust from the fuel, and 44 is an electromagnetic fuel pump. Reference numeral 46 denotes an electromagnetic fuel injection valve, and fuel pumped from the fuel pump 44 is supplied to this injection valve 46. Reference numeral 48 denotes a pressure regulator that keeps the pressure of the fuel fed from the fuel pump 44 to the injection valve 46 constant. That is, when the fuel pressure supplied from the fuel pump 44 to the injection valve 46 exceeds a predetermined pressure, the pressure regulator 48 opens and a portion of the fuel is returned to the fuel tank 40 via the pipe 50.

52 is a pressure detection device attached to the crankcase 18, which detects the crank chamber internal pressure P.

54 is a crank angle detection device attached to the crankshaft 20, which detects the rotation angle θ of the crankshaft 20.

In the implementation of the present invention, this crank angle detection device 54 detects the timing (θPI) near the opening of the scavenging boat 36.
It functions as a timing detection means for detecting timing (θP2) near a leap day.

56 is an intake air temperature detection device attached to the intake pipe 26, which detects the intake air temperature T.

58 is an air amount calculation device. The air amount calculation device 58 obtains the detection signals of the pressure detection device 52, the crank angle detection device 54, and the intake air temperature detection device 56, and detects the detection signal when near the scavenging port opening (θ
Using the crank chamber pressure P 1 of PI), the crank chamber pressure P 2 near the time when the il air port is closed (θP2), and the intake air temperature TO, the intake air amount G is determined based on the above-mentioned equation (5).

60 is an injection control device. The injection control device 6° receives the calculation result G of the air amount calculation device 58, the rotation angle θ of the crankshaft 20, and various control signals indicating operating conditions such as intake air temperature, engine temperature, acceleration/deceleration, etc. Injection control device 60
calculates the optimal fuel supply amount for the operating conditions according to a calculation program stored in advance in the injection control device 60, and outputs an injection signal to the injection valve 46. This injection signal I is an electric signal of a predetermined time width intermittently synchronized with the rotation angle θ of the crankshaft 20, and the electromagnetic solenoid in the injection valve 46 is actuated by this injection signal ■ to open the injection valve 46.
The injection control bag W60 determines the time width of the injection signal I to be optimal in accordance with the driving situation.

Of course, this injection control bag j180 can be constructed from a digital calculator, but it may also be constructed from an analog circuit.

Next, the operation of this embodiment will be explained.

As the piston 14 rises, the internal pressure of the crank chamber 24 decreases, and when the piston 14 opens the intake boat 3o, intake air flows into the crank chamber 24 via the reed valve 28.

When the piston 14 descends, intake air is pre-pressurized within the crank chamber 24, and when the scavenging boat 36 opens, this pre-pressurized intake air flows into the combustion chamber 12A through the scavenging passage 38 and pushes the burned gas into the exhaust boat 32. put out.

During this time, the air amount calculation device 58 is operated by the pressure detection device 5.
2, crank angle detection device 54, and intake air temperature detection device 56
Obtaining the detection signal of
Find G. The injection control bag fi60 calculates the calculation result G of the air amount calculation device 58 and the rotation angle θ of the crankshaft 20.
, and other various control signals, calculates the time width of the injection signal I that matches the optimum fuel supply amount. Fuel maintained at a constant pressure by a pressure regulator 48 is supplied to the injection valve 46, and when an injection signal is input, the injection valve 46 is opened for a certain period of time and an appropriate amount of fuel is injected into the combustion chamber 12A. do. Therefore, the air-fuel mixture generated within the combustion chamber 12A has an optimal concentration.

According to the above embodiment, when calculating the intake air amount G by the air amount calculating device 58, the above-mentioned equation (5) or a simplified equation
By using a numerical table, the amount of intake air can be detected with high precision, and as a result, the control accuracy of controlling the fuel injection amount according to the actual amount of intake air can be improved. A mixture concentration can be formed.

Incidentally, in implementing the present invention, the injection valve may be attached to the intake pipe (26), inject fuel into the intake pipe, and precompress the air-fuel mixture in the crank chamber.

Furthermore, in implementing the present invention, when detecting the crank chamber pressure Pl near the opening of the scavenging port and the crank chamber pressure P2 near the closing of the scavenging port, the opening/closing timing of the scavenging port does not necessarily depend on the crank angle as in the above embodiment. 0, which does not require detection based on the detection signal of the detection device
9-(By using the installation structure of the pressure detection device as described in the I875 publication, the pressure inside the crank chamber may be detected near the opening of the scavenging/port and near the closing of the port.

[Effects of the Invention] As described above, according to the present invention, in a fuel injection device for a two-stroke internal combustion engine with crank chamber preloading, the amount of intake air is detected with high precision, and as a result, the amount of fuel injection is adjusted to the actual amount of intake air. It is possible to improve the control accuracy of control according to the operating conditions and form the optimum mixture concentration corresponding to the operating state.

[Brief explanation of drawings]

The figure is a control system diagram showing one embodiment of the present invention. be. 10... Internal combustion engine, 12A... combustion chamber, 24...crank chamber, 36...Scavenging boat, 52...pressure detection device, 54...Crank angle detection device, 56...Intake air temperature detection device, 58... Air amount calculation device, 60... Injection control device.

Claims (1)

[Claims] (1) In a crank chamber preload type two-stroke internal combustion engine that prepressurizes intake air in the crank chamber and supplies the prepressurized intake air to the combustion chamber from the scavenging port, a pressure detection device that detects the pressure in the crank chamber and a pressure detection device that detects the intake air temperature are used. Obtain the detection signals of the intake air temperature detection device, the pressure detection device, and the intake air temperature detection device,
An air amount calculation device that calculates the intake air amount G based on the following formula using the crank chamber pressure P1 near the scavenging port opening, the crank indoor pressure P2 near the scavenging port closing, and the intake air temperature T0, and the air amount calculation device 1. A fuel injection device for an internal combustion engine, comprising: an injection control device that determines a fuel injection amount based on a calculation result. G=h[f(P1, P2), T0] However, f(P1, P2)=P2[(P1/P2)^1^
/^n-1]n: polytropic index